Polymer scale preventive agent

Abstract

A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising a condensation product of (A) hydrazine and (B) a quinone compound. Where the monomer is polymerized in a polymerization vessel having, on its inner wall surface, a coating comprising the condensation product, deposition of polymer scale can be effectively prevented not only on the liquid phase part in the polymerization vessel but also near the interface between the gas phase part and the liquid phase part, so that the thus obtained polymer can provide a molded item having few fish eyes and low in initial coloration, when the polymer is molded into a sheet or the like.

We claim: 
     
       1. A polymer scale preventive agent for use in polymerization of a monomer having an ethylenically unsaturated double bond, comprising a condensation product of (A) hydrazine, and (B) a quinone compound, said condensation product having been prepared by reacting the hydrazine (A) and the quinone compound (B) in an amount of 0.01 to 10 parts by weight per part by weight of said hydrazine (A) in a solvent under a total concentration of (A) and (B) of 0.5 to 20% by weight at a temperature of 25°-100° C. for 5 to 100 hours. 
     
     
       2. The agent of claim 1, wherein the component (B) comprises a quinone compound of one of the following formulas (1) to (4): ##STR3## wherein in the formulas (1) and (2), R 1  is --H, --NH 2 , --Cl, --Br, --OH, --NO 2 , --COCH 3 , --OCH 3 , --N(CH 3 ) 2  or an alkyl group of from 1 to 3 carbon atoms, R 3  is --H, --NH 2 , --OH, --CH 3 , --COOH or --SO 3  H. ##STR4## wherein in the formulas (3) and (4), R 1  and R 2  are as defined above, and R 3  is --H, --OH, --CH 3 , --Cl, --Br, --COCH 3 , --OCH 3 , --COOH or --SO 3  H. 
     
     
       3. The agent of claim 1, wherein the component (B) comprises at least one compound selected from the group consisting of p-benzoquinone, duroquinone, lawsone, juglone, α-naphthoquinone, and β-naphthoquinone. 
     
     
       4. The agent of claim 1, wherein the condensation product is in a liquid form wherein the condensation product is dissolved or dispersed in a solvent. 
     
     
       5. The agent of claim 4, wherein the solvent comprises water. 
     
     
       6. The agent of claim 4, wherein the solvent comprises a mixed solvent of water and an organic solvent miscible with water. 
     
     
       7. The agent of claim 6, wherein the proportion of the organic solvent in the mixed solvent is 50% by weight or below. 
     
     
       8. The agent of claim 4, wherein the concentration of the condensation product of the components (A) and (B) is in the range from 0.005 to 10% by weight. 
     
     
       9. A polymerization vessel for polymerizing a monomer having an ethylenically unsaturated double bond, which polymerization vessel has, on its inner wall surface, a coating comprising a condensation product of (A) hydrazine, and   (B) a quinone compound.   
     
     
       10. The polymerization vessel of claim 9, wherein said coating is formed not only on the inner wall surface but also on the other areas than the inner wall with which the monomer comes into contact. 
     
     
       11. The polymerization vessel of claim 9, wherein said coating is further formed on the areas with which unreacted monomers come into contact of a system for recovering unreacted monomers. 
     
     
       12. The polymerization vessel of claim 9, wherein the amount of the coating after dried is from 0.001 to 5 g/m 2 .